For industrial radiography a normal processing cycle is characterized by the following steps: transport of the film through the developer at 28° C., transport through the fixer at 26° C., transport through a rinsing bath and transport through the drying station. This normally takes a total processing time of about 8 minutes dry-to-dry. In order to decrease the total processing time, in order to approach a more desired “rapid processing” ability for requested more rapid examination ability, lowering of the gelatin amount coated, is a measure providing reduction of total processing time cycles from 8 minutes to 5 minutes. If an automatic processing machine is used therefor, film transport is made possible by the racks, each of which is provided with a lot of rollers immersed in different processing baths. In the said automatic processing machine “pressure sensitivity”, more particularly with materials having thinner vulnerable gelatin layers, becomes visible as a black dot or line in the processed material, thus disturbing or even making unambiguous examination impossible. More in detail it has been observed that pressure marks occur, in the processing steps, by contact of the material in the developer rack or in the so-called “cross-over step” from developer to fixer. This problem becomes more and more stringent when in the coated light-sensitive layers a decreasing ratio of gelatin to coated silver is calculated.
Coating materials with increased amounts of gelatin in the coating layers (thereby increasing the so-called “gesi” or ratio by weight of gelatin to silver) in order to avoid pressure marks may cause drying problems (as has discussed in EP-A 0 698 817) and may moreover cause “sludge” in the processing solutions during processing. This problem could be solved by addition of increased amounts of hardeners while coating the material, but other problems like loss in speed may occur. Further measures in order to compensate for the said loss in speed, like increasing the average size of the emulsion grains or crystals, however lays burden on the desired gradation or contrast, which is expected to decrease to an undesired level and which may cause image quality to deteriorate. Use of emulsions having silver bromoiodide emulsion grains, provided with a heterogeneous iodide distribution over the grain volume, in that a slightly increased amount of iodide is provided at the surface of the grains, may be in favor of less pressure sensitivity, but presence of iodide in higher concentrations in the outermost layers of silver halide emulsion grains may however lay burden on the developability of the grains and loss in speed or loss in rapid processing applicability. Moreover fixation of grains enriched with iodide at the grain surface may be worse, so that fixation times during processing may increase.